Technical Abstract:
Desiccation tolerance has been studied at the molecular level by examining tolerant systems such as resurrection plants and mosses. As a result of these studies, it has become apparent that tightly regulated programs of gene expression, both at the spatial and temporal levels, occur in vegetative tissues during drying. By using differential screening approaches, cDNAs corresponding to transcripts expressed only in response to water deficit have been isolated and characterized. However, it should be emphasized that, due to the purely descriptive nature of the data, the functional role of the gene products is unclear. Using examples from resurrection plants and the moss Tortula ruralis, this article reviews what is currently known about the molecular responses that occur during the acquisition of desiccation tolerance and how this knowledge may be applied to improve plant tolerance to limiting water conditions.